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C David

Publications and source records attributed to C David.

At least 19 recordsLinked to original sources
PubMed1992

Substrate specificity of the luminal Na(+)-dependent sulphate transport system in the proximal renal tubule as compared to the contraluminal sulphate exchange system.

The efflux of [35S]sulphate from the lumen of the proximal renal tubule into tubular cells of rats was measured by the stop-flow tubular-lumen microperfusion technique. The transport parameters obtained and the apparent Ki values of competing substrates were compared with those of the contraluminal influx of [35S]-sulphate from the interstitium into tubular cells. For the luminal sulphate efflux a Km(l, SO4(2-)) of 0.8 mmol/l and a Jmax(l, SO4(2-)) of 0.2 pmol s-1 cm-1 were found. The corresponding contraluminal values were Km(cl,SO4(2-)) 1.4 mmol/l and Jmax(cl,SO4(2-)) 1.2 pmol s-1 cm-1. Omission of Na+ from the perfusates reduced the luminal efflux of sulphate by 83%, while the contraluminal influx of sulphate was not changed. Increase in HCO3- concentration inhibited both luminal efflux and contraluminal influx of sulphate, while a change of pH from 6.0 to 8.0 was without effect. Comparing the apparent Ki(SO4(2-)) values for luminal and contraluminal sulphate transport, a relationship close to 1:1 was seen for some inorganic substrates with tetrahedral molecular structure (thiosulphate, sulphate, molybdate and selenate). The same holds for phosphate, while for oxalate the contraluminal Ki(SO4(2-)) value was lower than the luminal one (1.2 and 4.5 mmol/l). Some of the dicarboxylates and disulphonates tested show the same affinity to the luminal Na(+)-dependent sulphate transporter and the contraluminal sulphate exchange system, whereas most of the benzene carboxylate and benzenesulphonate derivatives tested exhibit higher luminal than contraluminal Ki values. The inhibitory potency increased with rising numbers of substituents on the benzene ring. This effect was more pronounced for the contraluminal sulphate transporter. In general, only disulphonates and analogues as well as similarly structured compounds (5-sulphosalicylate, 2-hydroxy-5-nitrobenzenesulphonate, eosine-5-isothiocyanate) have a good inhibitory potency toward the luminal sulphate transporter [apparent Ki 0.9-3.1 mmol/l]. All the tested sulphamoyl and phenoxy diuretics, and fluorescein and phenolphthalein dyes showed no or a smaller inhibitory potency to the luminal sulphate transport system than to the contraluminal. The most effective inhibitors of both sulphate transport systems are 8-anilino-1-naphthalenesulphonate, orange G, and H2-DIDS. The data indicate that the Na(+)-dependent luminal and the Na(+)-independent contraluminal sulphate transport systems accommodate a similar spectrum of anionic substrates, whereby the inhibitory potency against the luminal Na(+)-dependent sulphate transport system is identical or smaller than against the contraluminal transporter.

Animals↗
PubMed1992

Evidence for a correlation between auxin production and host plant species among strains of Pseudomonas syringae subsp. savastanoi.

Auxin production by 131 strains of Pseudomonas syringae subsp. savastanoi was investigated with the aim of looking for correlations among this characteristic and the origin of the strains, the types of symptoms, and the host plant. Most of the P.syringae subsp. savastanoi strains, except those isolated from ash, produced auxin and harbored iaa genes. Among ash strains, which were pathogenic only on ash, only 2 out of 33 were found to produce auxin and to harbor iaa genes.

Indoleacetic Acids↗
PubMed1991

The 3' promoter region involved in RNA synthesis directed by the turnip yellow mosaic virus genome in vitro.

We have previously shown that the last 100 nucleotides from the 3' end of turnip yellow mosaic virus (TYMV) RNA compete in vitro with genomic RNA for the TYMV-specific RNA-dependent RNA polymerase (RdRp). To further characterize the promoter on genomic RNA that produces complementary RNA strands, shorter fragments corresponding to the 3' region of the viral RNA were generated and used in in vitro assays. Fragments as short as 38 nucleotides corresponding to the 3' end of TYMV RNA compete with the viral RNA for the RdRp suggesting that the 3' promoter on plus strand RNA is probably less than or equal to 38 nucleotides long. These transcripts are themselves used as templates in vitro.

Base Sequence↗
PubMed1991

Antigenic mimicry and autoimmune diseases.

The finding of cross-reactive autoantibodies or sequence homology does not necessarily mean that this molecular mimicry is biologically meaningful or associated with disease pathogenesis. For example, relatives of persons with putative autoimmune insulin-dependent diabetes [123], and elderly humans [124] have a high incidence of autoantibodies which are generally not associated with autoimmune disease. In addition, natural antibodies to cell constituents [125] may be present in normal sera. These antibodies need to be directed against biologically important domains of host cell proteins in order to mediate autoimmune disease [27]. In spite of extensive homology between two sequences, a cross-reactive immune response may not be generated. The dissimilar amino acids should not be radical substitutions or affect the binding properties of the molecule. For instance, antibodies to synthetic peptides with only one substitution in a 19 amino acid sequence may not bind the whole protein [126]. Despite an identical six amino acid sequence shared by HLA-B27 and an EBV protein, no cross-reactive antibodies to EBV peptides were found in HLA-B27 positive patients with AS or RS. Unless the homology and subsequent crossreactive immune response can recognize a host protein intimately involved in disease pathogenesis, autoimmune disease is unlikely to occur.

Amino Acid Sequence↗
PubMed1991

[A new case of autochthonous visceral leishmaniasis in Bolivia].

A sixth autochthonous case of visceral leishmaniasis is reported in Bolivia. It is also the fourth case detected in the Yungas Valley (Department of La Paz) confirming the long-term existence of the disease in this area where cases of canine leishmaniasis and natural infestation of the phlebotomine sandfly, Lutzomyia longipalpis, were previously reported.

Antimony Sodium Gluconate↗
PubMed1979

Genetic control of experimental autoimmune myasthenia gravis in mice. I. Lymphocyte proliferative response to acetylcholine receptors is under H-2-linked Ir gene control.

As a first step in determining the genetic control of experimental autoimmune myasthenia gravis in mice, we tested the proliferative responses of lymph node cells to torpedo acetylcholine receptors (TAR). Studies with congenic and recombinant inbred strains of mice revealed that T-cell responses to TAR are controlled by an H-2 linked Ir gene, mapping in the I-A subregion of mouse major histocompatibility complex.

Acetylcholine↗
PubMed1978

Immune response-associated antigens on mouse leukemia cells. I. Detection of Ia antigens on GRSL cells.

The expression of immune response-associated (Ia) antigens on the surface of mouse strain GR (H-2dx) ascites leukemia (GRSL) cell lines was studied by cytotoxic tests, immunofluorescence, and immunoprecipitation assays. Ia expression varied among the three GRSL cells lines (GRSL 2, GRSL 14, and GRSL 15) studied by cytotoxic assay. GRSL 14 cells showed the strongest expression of Ia antigens among these three cell lines. A time-course study of tumor growth in mice revealed that Ia antigens on the tumor cells demonstrated the strongest expression 10 days after injection of GRSL cells into GR mice, and that subsequently it decreased until the death of the animal. Cells treated with neuraminidase exhibited more readily detectable Ia antigens, expecially in the late stages of leukemia, which suggested that Ia antigens had been masked by sialic acid. Immunoprecipitation studies revealed that Ia molecules on the leukemia cell had the same molecular weight as those on the normal lymphocytes. Immunofluorescence studies disclosed that Ia antigens were distributed diffusely on the surface of the tumor cells.

Animals↗
PubMed1977

Sampling survey on brucellosis among farmers and their families in Ille-et-Vilaine (Brittany).

A three-stage sampling survey among farmers and their families living on farms in the department of Ille-et-Vilaine gave the following results: Among 490 persons examined 313 (64 per cent) showed a positive skin test and 105 (21 per cent) a positive serological reaction; 88 of the 105 patients ignored their health status, although 45 of these presented clinical symptoms (nine per cent). This survey is continuing in order to study the non-respondents and to better analyse the epidemiological situation at a farm level.

Adolescent↗
PubMed1977

Homonymous hemianopsia and rehabilitation in fifteen cases of C.C.I.

Fifteen cases of severe cranio-cerebral injuries (C.C.I.) with hemianopsia and rehabilitation problems are presented. The correlation between the side of the hemianopsia, dexterity, visual motor organization, intellectual functions and rehabilitation outcome are discussed.

Brain Injuries↗
PubMed1976

Expression of individual Ia specificities on T and B cells. I. Studies with mitogen-induced blast cells.

Ia specificities 1-10 were detected on LPS-stimulated splenic lymphocytes and on Con A-stimulated spleen, lymph node, and thymus blasts by direct cytotoxic tests. Since Ia antigens are not readily detectable on resting thymocytes, our results suggest that T cells require some signal before they exhibit full expression of Ia specificities. Absorption-elution studies indicated that most of the Ia specificities detected on T and B cells may be identical. Ia antigens detected by homologous antisera gave much stronger reactions than those detected by cross-reacting antisera.

Animals↗
PubMed1976

Separation of anti-Ia (I-region associated antigens) from anti-H-2 antibodies in complex sera, by absorption on blood platelets. description of three new Ia specificities.

H-2 antigens are expressed in substantial amounts of murine blood platelets (for H-2 antigenic content 1 lymphocyte approximately 50 platelets) whereas Ia antigens are probably not expressed at all (minimal Ia antigenic content more than 35 times lower than for H-2). This property of blood platelets makes them very useful for the selective absorption of anti-H-2 antibodies from complex sera and for the preparation of specific anti-Ia antibodies from such sera. In 20 sera produced against the complete H-2 complex, 12 sera contained anti-Ia antibodies beside the expected anti-H-2 antibodies. In two sera, separation of the anti-Ia antibodies was easily obtained by absorption of the anti-H--2 antibodies on platelets. The analysis of one serum (C3H.Q X B10.D2) anti-C3H [(q X d) anti-k] showed that, in addition to be expected anti-H--2.23 and anti-Ia.2 antibodies, it contained at least three other Ia antibodies, separable by absorption on lymphocytes, which recognized three antigens--Ia.17, determined by the haplotypes k, f, s, r, j; Ia.18, determined by the haplotypes k, f, s; and Ia.19 determined by the haplotypes k and r. The genes are located in the I--A and/or I--B subregions of the H--2 complex.

Absorption↗
PubMed1976

The outcome of staphylococcal bacteremia in childhood. "The prognosis is better than previously reported".

Fifty infants and children were treated for staphylococcal infections complicated by bacteremia. Of these, 28 had serious underlying diseases, principally leukemia (15 cases). All were treated with intravenous antibiotics for a median duration of 12.7 days. Although 13 patients died (26%), the staphylococcal infection had apparently been eradicated in all but three (6%), one of whom died before treatment could be started. The relatively brief treatment periods required in even severely compromised leukemic patients and the survival of all but one of 22 previously healthy patients with staphylococcal bacteremia suggest that the prognosis is better than previously reported.

Anti-Bacterial Agents↗
PubMed1975

Recovery of a new herpesvirus from the ground squirrel (Citellus citellus).

A new herpesvirus recovered from the kidneys of mature ground squirrels (Citellus citellus) produced an effect in tissue culture cells resembling that of herpesviruses, including the formation of multinucleated syncytia and type A intranuclear inclusions. The isolate caused latent infection in the natural host, but it proved fatal for intracerebrally inoculated suckling mice and it produced pocks on the chorioallantoic membrane of embryonated eggs. Electron-microscopic examination of infected cells revealed intranuclear virus particles exhibiting a size and ultrastructure characteristic of herpesviruses. The isolate was ether-resistant and a DNA nucleic acid type was inferred from observations on inhibition by fluorinated pyrimidine. This ground squirrel herpesvirus was found to be antigenically distinct from Herpesvirus hominis and from ground squirrel cytomegalovirus, with no detectable cross-reactivity.

Animals↗